TAZs and Socioeconomic Data

The Traffic Analysis Zone (TAZ) layer is a geographic unit that represents a small area within the Metrolina region. It stores information related to the socioeconomic database and serves as the origin and destination for all tours. Each TAZ has a TAZ ID number that can be joined with the socioeconomic database.

TAZ Database

The TAZ structure consists of 3,896 zones and spans 13 counties. Each TAZ is connected to the highway networks by centroid connectors. The TAZs were updated to reflect changes to the 2020 US Census block data.

External zones are defined using a polygon-based method. This means external stations are drawn as cordon TAZs just outside the study area, where traffic enters and leaves.

Socioeconomic Database

The Socioeconomic (SE) or land use data is a primary an input into the travel demand model. The SE data consists of estimates of population, households, student enrollment and employment. This information was developed by ….

The household data consists of:

Households
Total Population
Household Population
Median Household Income
Group Quarter Population

The employment data consists of eight primary categories of employment and correspond to the the North American Industry Classification System (NAICS).

Low-Traffic Industrial Jobs
High-Traffic Industrial
Retail
High-Traffic Retail
Low-Traffic Service
High-Traffic Service
Education
Office

View MRM - NAICS

Area Type

Area type is one of the inputs to the speed and capacity calculations of the network. Area type is calculated based on residential and employment density within a 1.5-mile radius of the TAZ center.

Each TAZ is assigned one of five area types:

Central Business District (CBD)
Central Business District Fringe/Other Business District (OBD)
Urban
Suburban
Rural

The table below shows the criteria used for each area type.

	Employment Density (Employment/Square mile)
Population Density (Population/Square mile)	0-2,600	>2,600	>10,500
Less than 375	Rural (5)	CBD Fringe/OBD (2)	CBD (1)
Greater than or equal to 375	Urban (3) - If POPDEN + EMPDEN/1.6 is greater than 2,100 Suburban (4) - If POPDEN + EMPDEN/1.6 is less than or equal to 2,100	CBD Fringe/OBD (2)	CBD (1)